The present invention relates to an optical apparatus used for a laser device for operation.
A laser knife for medical use condenses rays of laser of high output, for example, such as rays of CO.sub.2 laser, and, by utilization of high temperatures then produced, vaporizes or solidifies a composition composed of protein or the like to effect operation. Since such laser knife for medical use possesses several advantages noted below, it is now increasingly used in field of surgical treatment.
(1) It offers styptic effects. PA1 (2) Micro-surgery can be effected. PA1 (3) Influence on those other than the affected part is minimal. PA1 (4) Non-contact surgery can be effected.
In view of further advantages such that the diameter of the condensed beam of laser is very small and that the rays of laser may be introduced by the optical system into a deep part in a state of non-contact, micro-surgery laser operating apparatus, which is safety and easy in handling, has been demanded in the fields of cranial nerve surgery, otorhynoloaryngologist, and obstetrician, who must operate the deep part of the body.
To fulfill such demands, a few processes have been proposed lately. A first process is that rays of laser condensed by an infrared ray transmission lens are introduced to the affected part by a plane reflector fixed frontwardly of an objective lens of the microscope, and the sight of the laser beam is adjusted by moving the entire microscope up and down, right and left, and back and forth.
A second process is that rays of laser condensed by an infrared ray transmission lens are introduced to the affected part by a light introducing 45.degree. reflector, which is designed so that it can be moved slightly in front of an objective lens of the microscope, and the sight of the laser beam is adjusted by varying an angle of the 45.degree. reflector. This process is described in detail in Japanese Patent Laid-Open No. 8085/1974, entitled "Stereoscopic Laser Endoscope".
However, according to the above-described two processes, the rays of laser are commonly condensed by the lens and therefore, they are unavoidably sufferred from out-of-focus of the condensed spot resulting from a slight transmission loss of the rays of laser and spherical aberration. Also, in the first process, in which the entire microscope is moved, there poses problems such that it is difficult to effect fine or slight movement if manual operation is employed, and that a large apparatus must be used if power operation is employed. Even in the second process, in spite of the fact that a mechanism, by which the angle of the introducing 45.degree. reflector positioned in front of the objective lens is varied without impairing the range of field through an eyepiece, becomes complicated, it was impossible to allow the 45.degree. reflector to effect its elevation movement and horizontal rotation in a completely independent manner when the reflector is shaked thereabout. This means that the sight of a laser spot cannot smoothly be adjusted to the target position by operating a single stick (a maneuvering lever). For example, it poses a problem such that even when the stick is moved laterally, the laser spot will move not only laterally but vertically.